The Person in Medieval Thought

Thomas Aquinas (1225-74), the most influential of Catholic
theologians, developed a largely Aristotelian conception of the
person, but he also needed to make some qualifications. While
he believed Aristotle's philosophy helped Christians to appreciate
Christian teaching on the resurrection of the body, he still believed
that Christian doctrine required an immortal soul to which the
body would be restored at the general resurrection. Thus, he argued
(and not very cogently) that Aristotle was wrong about the mortality
of human souls.

Aquinas theoretical approach to the nature of the soul
was to ask, first, in what kinds of activities do people engage.
Then, he identified the kinds of operative powers needed to explain
such actions. Finally, he concluded as to the sort of entity needed
to account for all of these powers. The activities that he recognized
included the biological functions of growth, assimilation of food,
and reproduction. A higher set of activities included sensation,
emotional responses to perceptions, and locomotion. But the highest
faculties of all were the cognitive functions of understanding,
judging, and reasoning -- along with the ability to be attracted
to the objects of the understanding (will). This latter faculty
is what accounts for human moral capacities, as well as for the
attraction to God.

We can see that medieval theology drew on the prior Greek speculations.
It did not seem possible to attribute human powers to the body,
so theories were developed about an additional component of the
person to account for them, e.g., the soul. Further, since living
persons can perform the human capabilities and corpses cannot,
the soul was also taken to be the life principle.